Emission control devices, such as diesel particulate filters (DPF), may reduce the amount of soot emissions from a diesel engine by trapping soot particles. Such devices may be regenerated during operation of an engine to decrease the amount of trapped particulate matter. Regeneration is typically achieved by raising the temperature of the DPF to a predetermined level, and ensuring that the exhaust gas entering the DPF is of a certain composition.
One approach for regenerating a DPF includes injecting fuel into an exhaust stream after a main combustion event. The post-combustion injected fuel is combusted over catalysts placed along the exhaust stream. The heat released during the fuel combustion on the catalysts increases the exhaust temperature, which burns the trapped soot particles in the DPF.
However, the inventors herein have recognized potential issues with such systems. As one example, the above-described approach can result in a higher temperature increase than desired, which may be detrimental to the exhaust system components, including the DPF. The process also requires additional fuel consumption as fuel needs to be injected for the DPF regeneration to take place. Furthermore, high pressure loss may be observed due to soot deposition at both the inlet and outlet of the DPF, and in some configurations due to flow through channels within the DPF and through the porous walls comprising the channels of the DPF.
In one example, the issues described above may be addressed by a particulate filter including a filter body, a first rolling guide and a roller heater, each housed within the filter body, a particulate-trapping material extending from the first rolling guide to the roller heater, and an exhaust inlet with the particulate-trapping material extending across the exhaust inlet. The particulate filter may be coupled to an exhaust passage of an engine system with exhaust from the exhaust passage entering the particulate filter through the exhaust inlet, exhaust flowing across particulate-trapping material and exhaust flowing out of the particulate filter through an exhaust outlet. The exhaust flow through the exhaust inlet may be perpendicular to exhaust flow through the exhaust outlet.
An example method of using the particulate filter in an exhaust passage of an engine may include, during a soot loading phase, trapping soot from an exhaust stream of an engine via a filter paper loop inside a filter body of a particulate filter, the exhaust stream flowing through the filter paper and exiting through an outlet of the particulate filter, and responsive to a pressure difference across the particulate filter above a threshold, initiating regeneration of the particulate filter by activating a roller heater inside the filter body to move the filter paper loop past a heater of the roller heater.
In this way, the particulate filter may be regenerated by activating the roller heater to move the particulate-trapping material (e.g., filter paper) in proximity to the heater to burn the trapped soot from the particulate-trapping material. In doing so, injection of fuel in the exhaust stream flowing through the particulate filter is avoided, thus increasing fuel economy and lowering emissions. Further, the particulate filter only traps soot at the inlet and does not trap soot at the outlet, and the filter does not rely on channels, thus lowering the pressure drop across the filter. Additionally, the exhaust exiting the particulate filter may be relatively low temperature exhaust, as high temperatures are not utilized to regenerate the particulate filter and further because the exhaust flowing through the particulate filter may not flow past the activated roller heater while exiting the particulate filter. Further still, the above-described configuration of the particulate filter may allow ash generated during regeneration of the particulate filter to accumulate inside the filter body rather than on the particulate-trapping material, avoiding the need to remove ash from the particulate-trapping material.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.